Summary: Cell-free protein synthesis and two-dimen sional gel autoradiography were used to characterize early postischemic protein synthesis in rat neocortex. Severe forebrain ischemia was induced for 30 min (four vessel occlusion model) and followed by 3 h of recircula tion. Polysomes were isolated from the cerebral cortex, translated in vitro in a reticulocyte system, and analyzed by two-dimensional gel electrophoresis. The translation products of postischemic polysomes included a major new protein family (70 kDa) with multiple isoelectric variants that was found to comigrate with the 68-to 70-Energy failure during transient ischemia blocks protein synthesis, but when recirculation occurs, protein synthesis is impaired for at least 12-24 h after restoration of energy stores (Kleihues et aI., 1975;Cooper et al., 1977;Dienel et al., 1980; Nowak et aI., 1985). In contrast to reduced produc Dr. Kiessling's present address is Abteilung Neuropathologie, Pathologisches Institut, Albertstr. 19,7800 Freiburg, F.R.G.Abbreviations used: LSD, lysergic acid diethylamide; mRNA, messenger ribonucleic acid.
505kDa "heat shock" protein synthesized from polysomes of hyperthermic rats. Two other stress proteins (93 and 110 kDa) also appeared to be synthesized in increased amounts after ischemia. A complement of proteins that was indistinguishable from that of controls was also syn thesized after ischemia, indicating that messenger ribonu cleic acid coding for most brain proteins is preserved after ischemia and is bound to polysomes. Key Words: Brain ischemia-Heat shock proteins-Hyperthermia Protein synthesis. other brain proteins . Hyperthermia and other injurious or noxious treatments that in crease ornithine decarboxylase activity in rat brain, liver, and kidney (Dienel and Cruz, 1984) are also known to stimulate the synthesis of heat shock pro teins in rat tissues (brain, liver, heart, adrenals, etc.), in tissue culture cells, and in many other or ganisms (Ashburner and Bonner, 1979;Currie and White, 1981; Cosgrove et aI., 1982; Schlesinger et aI., 1982). In addition, a 71-kDa heat shock protein is synthesized in rat brain, liver, and kidney after carotid ligation of one animal (Currie and White, 1981) and in rat brain slices subjected to the isch emia of decapitation and tissue-slicing injury (White, 1980;1981).The purpose of this study was to determine if ri bonucleic acids (RNAs) coding for heat shock pro teins are being translated shortly (3 h) after post ischemic reperfusion when the rate of protein syn thesis is reduced by >50% and when ornithine decarboxylase activity is just beginning to increase (Dienel et aI., 1985a). We show that disaggregated poly somes derived from 3-h postischemic rat brain contain the messenger RNA (mRNA) coding for the normal complement of brain proteins and, in